When storing or transferring data, error correction schemes may be used to add extra information (AKA redundant data) to allow detection and/or correction of errors in the data when the data is later retrieved or received.
The detection and correction of errors may be required because data retrieved from memory devices, such as for example flash devices (including inter-alia NAND AND or NOR flash with or without multiple bits per cell), DRAM memories, 1 T on-chip memories, SRAM memories (including inter-alia in a low voltage silicon process), magnetic medias, and/or data transferred over a communication channel may have errors due to various reasons. Reasons for errors include inter-alia, radiation, random errors caused by noise and other reasons, errors caused by defective bits, and/or any other reason that may cause data loss at the time of the write, at the time of the read, at the time of the transfer and/or over time if the data is stored in memory. Factors which in some cases may cause variations in memory data retention (i.e. variations in data loss over time) include inter-alia process variations and the device life cycle (endurance).